Method of making sewing machine needles



Feb. 27, 1934. E. K. BROWN 1,949,350

METHOD OF MAKING SEWING MACHINE NEEDLES Original Filed Jan. 12, 1953Jfl' ll MW M 2 EJZmaRcZATBI-Oww 7 I; I 4,

Patented Feb. 27, 1934 BEETHOD OF MAKING SEWING MACHINE NEEDLES EdmundK. Brown, Torrington, Conn, assignor to The Torringtcn (Jompany,Torrington,

Conn, a corporation of Connecticut 4 Claims.

This invention relates to improvements in the art of sewing machineneedles, and more particularly to a construction of the same wherebygreater strength is assured in the blade of the needle with acorresponding increase in the strength of the structure adjacent theneedle eye, along with a lesser liability of breaking the needle threadduring the operation of the needle.

it has heretofore been the practice to form a needle with a body wire ofround cross-section by, for example, milling a long thread groove in itslength and a short thread groove at the eye. These thread grooves mustbe of sufiicient width and depth to bury the thread during sewing, so

' that the bight or" the thread at the eye is not exposed to directcontact with the fabric when the needle passes through the fabric, andso that the portion of the thread extending from the eye toward thesewing machine spool is contained within this longer thread grooveduring the entire course of movement of the needle into the fabric. Inorder to have the thread grooves of sufficient depth, with such acircular cross-section, the web left in the body between the grooves wasof restricted thickness, and hence it presented at the eye aninsuficient surface to the thread, and the thread was often broken atthe relatively sharp edge in the eye, by the effect of a thread tensionwhich was desirable for a proper drawing of the thread loops duringsewing.

Furthermore, with such a needle, the grooving of the metal to providespace for burying the thread results in a serious reduction of theradius of gyration of the needle, considered as a loaded column, so thatthe needle has a much lesser resistance against bending in the plane ofsymmetry through the thread grooves. Hence greater bending occurred, andbreakage of the needle is a frequent result. It is especially to benoted that this grooving not only removes much of the metal in thisplane, but also the metal remaining at the sides of the long threadgroove is very thin and hence has little ability to resist the bending.

These difficulties are intensified when two long thread grooves areemployed.

When it is sought to avoid these defects by employing a body wire ofsufiiciently large size to provide an ample web thickness and radius ofgyration, the cross-sectional area and perimeter become so great thatthe fabric is damaged, and the increased displacement of the fabriccauses a greater resistance to penetration and a greater wear. Thethinness of metal at the sides of the grooves is overcome but slowlywith increase of diameter of the body wire, with such a circularcross-section. If the grooves are made shallower, the thread is nolonger buried therein, and skipping of stitches and breakages of threadoccur from contact of thread and fabric.

When it is sought, by forging or som other process, to deform the bodywire at the location of the eye by extending the periphery thereatoutside of the general circular periphery of the body Wire itself, theincreased cross-sectional area and perimeter requires a larger hole inthe fabric for the passage of the portion of the needle adjacent theeye, and the fabric is thereupon momentarily permitted to return by itselasticity when this enlarged portion has passed the fabric and only thenormal diameter of the body wire is presented to the fabric. The bladeportion of such a needle, however, is no stronger than a needle made inthe accepted manner as described above, and bending and breakage occurs.Further, such conformation of the needle may only be produced by aforging or striking operation. The delicate dies required for theneedles, especially in the finer sizes, are apt to break, and soon wear.The forging operation, in the plane of the eye, causes the formation ofa flash or fin at each side, which must be removed by a further andseparate trimming operation. Such needles are, therefore, likewise notwholly satisfactory in service, and are expensive to manufacture.

According to the present invention, the needle is provided with agreater thickness of web between the thread grooves at the eye, and agreater radius of gyration is provided both at the eye as compared tothe accepted needle, and along the blade portion between the eye and theshank as compared with any prior needles. These results are attained bya simple and direct method of manufacture which does not requireextensive forming dies nor trimming operations.

According to the present method a body wire is formed with an oblongcross-section having a greater diameter along a major axis than along aminor axis, prior to the cutting of the grooves, and then these groovesare out along the major axis plane to an ample depth for fully buryingthe thread and yet a sufiicient web thickness is left between them foravoiding an edge at the eye so sharp as to cause a cutting or breakingof the thread, and then an eye is formed between the grooves throughthis web, without substantially changing the form or dimensions of thebody along the minor axis.

The needle according to this invention therefore may have the mostdesirable cross-section from the taper of the point back toward theshank for the entire distance by which the needle may enter or passthrough the fabric. My copending and parent application Serial No.651,435, filed January 12, 1933 discloses and claims this needle.

One form of construction of the needle, in which illustratively theneedle has a substantially uniform cross-section at the eye and alongthe blade, with a procedural representation of steps for the manufactureof the same, is shown on the accompanying drawing, in which:

Fig. 1 is a side elevation of a blank for the needle, as formed inmanufacture.

Fig. 2 is a cross-section of this blank at line 2-2 of Fig. 1, being atthe point where the needle eye is later to be formed.

Fig. 3 shows the deformation or flattening of the blank of Fig. 1, thissection likewise being taken at line 2-2 of Fig. 1.

Fig. 4 shows a further step of manufacture, in which the needle grooveshave been formed.

Fig. 5 shows the final stage of forming, in which the eye has beenpierced.

Fig. 6 is a longitudinal sectional view, substantially on line 6-6 ofFig. 5.

Figs. '7 and 8 are respectively side elevations in the directions of thearrows '7 and 8 of Fig. 6, showing a preferred shape for the threadgrooves.

The present needle is constructed from a blank which has been given anoblong cross-section for the entire length of the body between shank andpoint, and the thread grooves are formed along the major axis plane ofsuch cross-section. A presently preferred manner of manufacturing aneedle according to this invention comprises the formation of a blankhaving a circular cross-section, in the usual way. Such a blank is shownin Fig. 1 as having a shank 10 by. which it may be held in the needlebar clamp, and a tapering portion 11 joining this shank proper to thebody Wire 12.

This blank may be formed by swaging to produce a body wire of circularcross-section as shown in Fig. 2. While the normal gauge of body wirefor forming a needle is the same size as the finished needle, accordingto the present invention, this body wire is preferably ten percentgreater in diameter than the standard diameter selected for the finishedneedle.

In this preferred form of manufacture, the body wire is now flattenedfor its entire length by the operation of smooth surfaced dies, untilthe distance between the diametrically opposite flattened sides isreduced substantially to the desired diameter of the finished needle.The body thus assumes an oblong cross-section as shown in Fig. 3, inwhich the minor axis is the desired finished diameter, while the majoraxis diameter is considerably greater. This deforming between smoothdies, furthermore, gives a better surface than can be obtained bymilling and/or grinding, with lesser frictional effects and wear.

The thread grooves may then be formed in this flattened blank,preferably by milling as this furnishes a groove of definitelydetermined shape and dimensions. The illustrated long groove 15 isformed for the length of the body wire and extends up onto the taperedportion 11, this long thread groove having its side walls as nearlyparallel as feasible with a milling cutter, in this preferred form.Diametrically opposite this long thread groove at the location for theeye is formed, in the illustrative example, a short thread groove 16which is illustrated with slight tapered walls to permit the thread arelative angular movement about the longitudinal axis of the needleduring cooperation with the looper mechanism.

The web 1'7 which forms the bottoms of the two thread grooves is thus ofample thickness between the grooves.

An eye is now formed in this web, with the usual rounded edges, withoutsubstantial deformation of the oblong external cross-section at the eye.The usual polishing operation now rounds ofi the edges of the grooves,during which no substantial change of dimensions occurs, owing to thelarge angle between the peripheral surface and the side walls of thegrooves.

The substantially parallel walls of the long thread groove meet theperipheral surface of the body wire at edges which (Figs. 7 and 8) aresubstantially straight from end to end in the specific form illustrated,and thus afford a groove within which the portion of the threadextending from the eye toward the machine spool may be buried with theleast possible removal of material at this critical point.

The width of the groove is standard for the needle size, and thematerial removed from the body at the major axis plane of thecross-section of the blank, with such proportions and manufacture of theneedle, reduces it to substantially the same chordal dimension as theaforesaid minor axis diameter of the blank, and thus to the desiredfinished diameter of such a needle; (that is, the diameter between theflattened diametrically opposite surfaces is substantially the same asthe distance from one longitudinal edge 18 of one thread groove to thesymmetrical edge 19 of the other thread groove, measured along a chordof the cross-section).

This preferred manner of forming the body of oblong section is describedas flattening in accordance with the usual technical terminology, but itmust be understood that this flattening" is not limited to the formationof diametrically opposite plane portions but comprises generally theformation of oblong sections having different diameters along major andminor axes. result of this flattening is to displace metal so that thediameter along any diagonal (i. e. in any plane-other than the major andminor axis planes) is greater than the minor axis diameter. Therefore,when metal has been removed to form a groove, and thus the chordaldimension reduced as aforesaid to the minor axis diameter, the diametersalong such diagonals (a and b, Figs. 3 and 5) remain greater than theminor axis diameter, and also greater than the aforesaid chordaldimension. Thus a considerable quantity of metal remains in thestructure to provide the side walls of the grooves, and as this metal isat a maximum distance from the center axis of the needle, the effectiveradius of gyration is increased and a much stiffer needle results.Hence, the finished needle is more resistant to bending, and hence lessliable to breakage.

The method thus lends itself to a simple and accurate production of suchneedles without the employment of expensively manufactured and delicatepunching tools for forming the grooves adjacent the eye without theforming of any flash which must be removed, and without the sacrifice ofmaterial from the body at this weakest point of the sewing machineneedle. The needle produced is characterized by the oblong cross-sectionbetween point and shank taper, and by the thickness of web and largeradius of curvature permitted at the eye.

The

It is obvious that the invention is not limited to the formation ofconstruction and manufacture shown and described, but that it may beemployed in many ways within the scope of the appended claims.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:-

1. The method of making a sewing machine needle which includes thesuccessive steps of forming a needle body wire having an oblong crosssection, thereafter forming diametrically opposite thread grooves insaid body wire along the major axis plane thereof while maintaining thecross-sectional shape of the body wire substantially unchanged, and thenforming an eye in the web constituting the bottoms of said grooves.

2. The method of making a sewing machine needle which consists indeforming a body wire of circular cross-section larger than the finisheddiameter to be given the needle to an oblong cross-section in which theminor diameter corresponds to the said finished diameter, forming threadgrooves in said body wire along the major axis plane of saidcross-section with at least one of said grooves having substantiallyparallel side wall surfaces and so that the chordal distances between anedge of one said groove and the symmetrical edge of the other saidgroove is substantially equal to the said finished diameter, and formingan eye in the web constituting the bottoms of said grooves.

3. The method of making a sewing machine needle which includes deforminga body wire of circular cross-section larger than the desired finisheddiameter to form an oblong cross-section whose minor axis is of thedesired finished diameter, and removing material at the ends of themajor axis of the cross-section until the needle has chordal externaldimensions at the eye substantially equal to the desired finisheddiameter while forming diametrically opposite thread grooves along themajor axis plane.

4. The method of making a sewing machine needle which includes deforminga body wire of uniform circular cross-section larger than the desiredfinished diameter to form for the entire length thereof an oblongcross-section whose minor axis is of the desired finished diameter, andcutting diametrically opposite thread grooves along the major axis planeof the cross-section, at least one of said grooves having asubstantially uniform width through its length at the needle periphery.

EDMUND K. BROWN.

